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Posts Tagged ‘Arundo donax’

A study was published earlier this month in the journal Frontiers in Ecology and the Environment on the effects that invasive species have on other species around the globe. The study is by Tim M. Blackburn, Celine Bellard, and Anthony Ricciardi, and it can be found here.

The main thrust of the paper is that invasive species of plants and animals have been found to have a significant impact on the extinction of other plants and animals all around the world. Specifically, 25% of the plant species that have gone extinct in recent years have been the result, at least in part, of invasive species. Additionally, 33% of the animal species that have gone extinct in recent years have been the result, at least in part, of invasive species.

These numbers are pretty compelling components to the story of just how damaging invasive species can be. It is part of the reason I find working on invasive species control in California to be rewarding.

I am currently working on the control of Arundo (which is a large invasive reed), water primrose (an invasive aquatic plant), Phragmites (which is another invasive reed that is a bit smaller than Arundo), and Nutria (which is a 20 pound semi-aquatic rodent). Each of these species pose unique threats to the native species of California and to many other aspects of the ecosystem as well.

Hopefully, protocols can be developed to stop invasive species before they contribute even more extinctions!

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This is a link to a blog post I wrote for the UC Davis-USDA Delta Region Areawide Aquatic Weed Project website. The Sacramento-San Joaquin Delta Conservancy (the agency I work for) gets funding from the USDA to control Arundo infestations in the Delta.

Arundo (which I have written about previously here) is a highly invasive plant that causes bank destabilization, increased fire hazard, increased water use, and excludes native plants and animals. The Delta Conservancy has been coordinating with a the Sonoma Ecology Center and the USDA to apply treatments of herbicides and/or insects that are specific Arundo parasites to eliminate Arundo from as much of the Delta as possible. This work began last summer/fall at the Brannan Island State Recreation Area, as site that is owned by California State Parks and which has a lot of Arundo.

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I have been working at the Sacramento-San Joaquin Delta Conservancy for about four months now, and it occurred to me that I have not shared much of what the Delta Conservancy, and I in particular, have been doing in that time. My start here has certainly included a steep learning curve as I have become more familiar with the agency, my coworkers, and the many projects that the Delta Conservancy is pushing forward.

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Figure 1. A stand of Arundo.

I am starting to feel my feet under me, and wanted to share some the projects I am working on. So, first up is the Arundo Control and Restoration Project. This is a project that was started before I was hired and was managed by one of the other employees here at the Delta Conservancy. About a month after I started working here, she took a job elsewhere, and the Arundo Project was transferred to me.

Arundo donax, or Giant Cane, is an invasive plant native to the Mediterranean and Middle East, and which was introduced to southern California for building material and in the hope that it would grow along levees and help with flood and erosion control. Unfortunately, while it did grow extensively along levees, it did not help with flood and erosion control. Instead, it actually had the opposite effect. While it will grow into dense mats, these mats have shallow root systems, so when high flows occur, the strong currents tend to rip off large chunks of Arundo which then rips off large chunks of the levee underneath. Additionally, Arundo forms dense mono-culture stands, out competes native vegetation, and provides little useful habitat.

To start to remedy the situation and role back these negative effects, the Delta Conservancy’s Arundo Control and Restoration Project was founded.

Arundo Sites in the Delta - Map

Figure 2. Map of Arundo donax sites in the Delta (Young et al. 2015).

The overall plan is to figure out where Arundo is growing in the Delta, prioritize those sites to figure out which could provide the highest value habitat if the Arundo was removed, remove Arundo, and replace it with restored native vegetation. The native vegetation will be restored on the same areas where Arundo is removed from, except where this is not feasible due to landowner restrictions and land use policies. When it is not possible to directly replace existing Arundo stands with restored vegetation at the same location, restoration will occur at nearby sites that will be prioritized according to their habitat value.

Contracting with the Sonoma Ecology Center, the Delta Conservancy has completed the map of Arundo sites in the Delta (Figure 2) and also prioritized those sites according to their restoration value (Figure 3). As you can see in Figure 3, the darker the colored dot, the more potential value that area has if the Arundo is removed and native vegetation is restored.  

Arundo Sites in the Delta - Prioritized Map

Figure 3. Map of Arundo donax sites in the Delta prioritized by color (Young et al. 2015).

As is evident from these maps, there is quite a bit of Arundo in the Delta. Attempting to tackle all of it simultaneously seems a herculean task, so the total project was divided into two phases. Phase I is the pilot project phase. In Phase I we planned to locate a subregion of the Delta that contained Arundo, and develop our protocols and techniques to effectively control Arundo and implement habitat restoration work. Phase II would then be a significant expansion of Phase I into more regions of the Delta.

We are currently in the midst of Phase I. Based on the information in the above maps, and on opportunities to find land owners who had Arundo on their property and were willing to grant us access to work, the Delta Conservancy partnered with the Solano Resources Conservation District (Solano RCD) in identifying the Cache Slough Complex (CSC) as a prime region for Phase I to occur. We are currently working on a stretch of Ulatis Creek in Solano County. Ulatis Creek runs southeast out of Vacaville, CA for about 20 miles before emptying into Hass Slough and then into the Sacramento River. For almost all of its length, Ulatis Creek is constrained between levees on either bank. About 15 miles southeast of Vacaville, at a bend in the creek, there is an area where the levee on the north bank is set back a few hundred feet from the creek channel. In between this setback levee and the regular bank of the creek, and extending along the north shore, is an area of about 18 acres. Part of this 18 acres is covered in Arundo and the rest is used, intermittently, to graze sheep by the property owner.

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Figure 4. Ulatis Creek site. Sheep are grazing and the dense vegetation along the far edge is almost all Arundo.

This 18 acre area has been chosen, thanks to a willing private landowner, as the first stage of Phase I. In 2015, 3.77 acres of Arundo at the western end of the site were treated with an herbicide for the first time. Successful Arundo control has been shown to require two or three treatments to completely kill the plants in an area. This summer and fall, the Solano RCD will begin clearing non-native vegetation, laying out irrigation lines, and planting native vegetation. This native vegetation will take the form of somewhere on the order of 1500 trees of a mix of species and native understory species such as California Rose and Mugwort. Riparian trees will be planted along the perimeter of the site which will grow to shade the waterway and stabilize the banks. In the middle of the area, oaks and other upland tree species will be planted to create a more varied habitat pallet in the area. All these plants will then need several years of watering to make sure they are well established. This time also gives us the opportunity to replace plants that die.

If we are successful, and the removal of Arundo and establishment of native vegetation goes well, we will be well on our way to extending this effort to more areas of the Delta. Overall, this effort will replace areas of low habitat value and high potential for economic and environmental costs with areas of high habitat value that can be utilized by  a large range of species and better foster the ecosystem and sustainable economy of the Sacramento-San Joaquin Delta. I am excited to watch this project unfold as we move forward!

References:

Young, A., B. Sesser, and C. Liu. 2015. Delta Arundo mapping and prioritization. Sonoma Ecology Center.

 

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